Control of electric circuits



1942. J. A. SENN ETAL 2,297,991

CONTROL OF ELECTRIC CIRCUITS Filed Aug. 1, 1940 Patented Oct. 6, 19421,;

CONTROL OF ELECTRIC CIRCUITS Jurg A. Senn, Milwaukee, and Carroll Stansbury, Wauwatosa, Wis., assignors to Cutler-Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Application August 1, 1940, SerialNo. 349,206

14 Claims. This invention relates to the control of electric circuits and is particularly applicable to the synchronization ofthe operation of electromagnetic switches which in turn control translating circults.

An object of the invention is to provide a controller in which the moment of closure of a translating circuit can be accurately timed with re spect to the time-phase of the alternating supply voltage.

Another object is to provide a controller in which the moment of opening of the translating circuit can be controlled with respect to the time phase 01' the current flow in said circuit.

Another object is to provide a controller the moment of opening and/or closure of which is accurately controlled.

Another object is to provide a controller in which the time of opening and/or closure of a translating circuit thereby may be easily adjusted to meet various operating conditions.

Other objects and advantages will hereinafter appear.

The accompanying drawing is illustrative of an embodiment of the invention.

In the drawing,

Figure l is a circuit diagram of a system embodying the invention, and

Fig. 2 is a diagram showing the instantaneous currents flowing in various circuits of the system shown in Fig. 1.

Referring to Fig. 1, the same illustrates an alternating current supply circuit, having the lines L and L from which energy may be supplied through an electromagnetic switch I to a welding transformer 2. The switch I in turn is controlled by an electromagnetic relay 3 energizable through a normally open pushbutton switch as will be explained hereinafter.

, The electromagnetic switch I comprises a main magnet frame I and a cooperating pivoted armature l an auxiliary or lock-out magnet frame I and a cooperating armature i The armatures l and i are integrally united at a predetermined angle relatively to each other, and are pivoted about a pivot l The lever i controls a pair of normally open main contacts I. A main magnetizing coil l comprises two series connected sections l and I preferably surrounding the upper pole of frame l The up per pole of frame I is also provided with a shading coil winding I which is interlinked with only a part of the pole face in the usual manher.

The lock-out magnet frame I is provided with a main magnetizing coil i which preferably surrounds the lower pole, and said lower pole is provided with a shading coil winding which is interlinked with only a part of the face of said, pole. The coils l and l are connected in series with each other. I

The translating circuit 2 comprises a welding transformer having a primary winding 2 and a secondary winding 2*. The relay 3 comprises an energizing winding 3", a normally open double-break contact 3 and a normally closed double-break contact 3. The double-break of contacts 3 and 3 is provided by use of bridging members 3 and 3 respectively.

The system is connected as follows: A circuit is adapted to be completed from line L through a normally open pushbutton switch I, energizing coil 3 to line L Upon energization of relay 3 another circuit extends from line L through contacts 3 and member 3', section I of coil i to line L while the entire coil I is included in a circuit or loop comprising a resistor 4, a variable reactor 5 and a condenser 6. The lefthand terminal of the section l of coil l which is common with one terminal of the condenser B is connected to the right-hand one of the contacts 3, while the bridging member 3 is connected to one terminal of the shading coil i The contact lever i is connected to the line L which is thus connected to the movable member of the contacts I, the stationary member of said contacts I being connected through winding 1' of transformer 2 to line L During deenergization of relay 3 a circuit extends from line L through contacts 3, member 3 and winding i to line L, while the shading coil I has one of its terminals connected to the right-hand one of the stationary contacts 39 and its other terminal of said coil 1 is connected with the bridging member 3 so that the shading coil is short-circuited when contacts 3 are bridged by member 3 The system operates as follows: With the lines L and L energized a current flows from line L through the coil l to line L thereby attracting the armature I and holding the switch I in a normally open position. The flux induced in the frame I also energizes the shading coil I which is short-circuited through the right-hand contact 3 and member 3* so that a current flows therein which produces a magnetic flux which is out of phase with the main flux.

If it is now desired to energize the translating circuit the push button I is depressed thus energizing relay coil 3 which opens normally closed contacts 3 and closes normally open contacts 3. Closure of contacts 3 completes'a circuit through the coil section l to energize the closing magnet, the current being suflicient to close the switch after the restraint of the look-out magnet I is removed. The opening of contacts 3 first removes the short-circuit of the shading coil I and as the voltage of this circuit is very low said shading coil is rendered ineffective instantly upon response of the relay 3, while an arc is formed upon and persists for an in-' terval between the contacts 3 and member 3 thereby maintaining a current flow from line L through the left-hand contact 3, bridging member 3, the shading coil I, the main magnet value at the moment B upon the cessation of winding l to line L. The current then flowing through the shading coil l is only a small fraction of the normal shading coil current flowing therein, so that it is substantially ineffective to maintain a pull on the lock-out coil when the current in I passes through zero with consequent extinguishment of thearc, and the look- I out magnet thereupon releases and the switch closes under the influence of the pull of the closing winding l It will thus be observed that the initial movement of the magnet closure takes place at a given moment of the alternating voltage impressed upon the lines L 'and L and inasmuch as the time element of the switch is substantially constant the contacts I, close and thus energize the transformer 2 at a given time-phase of the alternating voltage. If after-theswitch I has closed its contacts I it is desired to again open the same the push but-- ton switch 'I is released thereby deen'ergizing the relay coil 3 which in turn opens the contacts 3 and closes the contacts 3. The lock-out magnet l is designed in such a manner that its pull very rapidly decreases upon movement of the armature I away from the magnet frame l c so that with the switch I closed the pull of the lock-out magnet is insufliclent to substantially affect the opening of the switch I. Upon opening of the contacts 3' the shortcircuit on the shading coil I is opened as has been explained heretofore in connection with the shading coil I Also after .a brief moment the current through the coil section I ceases flowing: because of interruption of the are which forms between the contacts 3 and member 3* upon disengagement of the latter from the former.

6 being coordinated in such a manner as to form with coil I an oscillatory circuit cause continued energization of the coil I after cessation of current flow from the line. This maintains the magnet frame I energized and the armature l in the attracted position until the current in said oscillating circuit passes through zero value, whereupon the armature I under the influence of gravity and any other forces that may be applied thereto, begins to retract thereby quickly v However, the .values of resistance 4, inductance '5 and capacity modifying the constant of the oscillatory circuit,

current flow from the line through the contacts 3 and member 3 When the value of current i9 (Fig. 2 again passes through zero at the monet I may also be applied to the lock-out magnet I in place of the circuit arrangement for the latter shown in the drawing. Byan arrangement such as that just described the moment of closure of the switch contacts I may be more accurately timed and adjusted than with the system as illustrated.

It is further apparent that the lock-out magnet frame I and its related circuits may be entirely omitted, in which case only the opening of the switch contacts I is controlled in the manner aforedescribed.

What we claim as new and desire to secure by Letters Patent is:

1. An electromagnetic switch adapted to control an alternating current translating circuit,

" comprising an electromagnet, a main winding adapted to induce a flux in said magnet, a shading coil mounted on said magnet, and means to.

short-circuit said shading coil upon itself and to connect said main winding to a source of alternating current and to alternatively open said short-circuit and thereafter disconnect said main winding from said source.

2. An electromagnetic switch adapted to control an alternating current translating circuit,

' comprising an electromagnet having a frame and an armature, a main winding adapted to induce a flux in said magnet, a shading coil mounted on said magnet, and means to short-circuit said shading coil upon itself and to connect'said main winding to a source of alternating current and to alternatively open said short-circuit and there- 1 after disconnect said main winding from said source.

3. An electromagnetic switch adapted to control an alternating current translating circuit, comprising an electromagnet, a main winding adapted to induce a flux in said magnet, a shading coil mounted on said magnet means to shortcircuit said shading coil upon itself and to connect said main winding to a source of alternating current and to alternatively open said shortcircuit and thereafter disconnect said main windingirom said source, and an oscillating circuit connected to said main winding and adapted to temporarily maintain said flux after said main winding is disconnected from said source.

4. An electromagnetic switch adapted to control an alternating current translating circuit, comprising an electromagnet, a main winding adapted to induce a flux in said magnet, a shad-- ing coil mounted on said magnet, means to shortcircuit said shading coil upon itself and to connect said main winding to a source of alternating current and to alternatively open said short-circuit and thereafter disconnect said main winding from said source, and an adjustable oscillat- Y ing circuit connected to said main winding and adapted to maintain said flux after said main winding is disconnected from said source and until the alternating current reaches a given phase of its cycle.

5. An electromagnetic switch adapted to control an alternating current translating circuit,

comprising a pair of cooperating contacts connectable to a translating circuit, an electromagnet, a main winding adapted to induce a flux in said magnet to effect closure of said contacts, a

, shading coil mounted on said magnet, and means nectable to a translating circuit to control the same, a pair of electromagnets adapted when energized to effect the opening and the closing of said contacts respectively, each electromagnct being providedwith a main winding adapted to induce a flux therein, each electromagnet also having a shading coil, means individual to each magnet to short-circuit its shading coil upon itself and to connect its main windingto a source of alternating current and to alternatively open said short-circuit and thereafter disconnect the respective main winding from said source.

7. An lectromagnetic switch adapted to control an alternating current translating circuit comprising, a pair .of cooperating contacts, an electromagnet adapted to effect closure of said contacts, and a lock-out electromagnet adapted to maintain said contacts open, each of said magnets having a main winding adapted to induce a flux therein and a shading coil, means individual to each of said magnets adapted to short-circuit its shading coil upon itself and to connect its main winding to a source of alternating current Ii and to alternatively open said short-circuit and to thereafter disconnect said main winding from said source, and an adjustable oscillating circuit connected to the main winding of said first mentioned magnet and adapted to maintain the flux therein after said main winding is disconnected from said source and until the alternating current in the translating circuit reaches a given phase of its cycle.

8. An electromagnetic switch adapted to control an alternating current translating circuit, comprising a pair of cooperating contacts, a closing electromagnet and a lock-out electromagnet, each of said magnets having a main winding adapted to induce a flux thereinand a shading coil, means individual to each of said magnets adapted to short-circuit the respective shading coil upon itself and to connect the main winding to a source of alternating current and to alternatively open said short-circuit and to thereafter disconnect said main winding from said source, an adjustable oscillating circuit connected to the main winding of said closing magnet and adapted to maintain the flux therein after said main winding is disconnected from said source, and until the alternating current in the translating circuit reaches a given phase of its cycle, and means to energize one and deenergize the other of said magnets alternately.

9. An electromagnetic switch adapted to control an alternating current translating circuit, comprising an electromagnet, a main winding having a portion adapted when energized to induce a flux in said electromagnet, a shading coil mounted on said magnet, means to short-circuit said shading coil upon itself and to connect said portion of said main winding to a source of alternating current and to alternatively open said short-circuitand thereafter disconnect said portion of said main'winding from said source, and an adjustable oscillating circuit connected in series relation with the entir main winding in the form of a closed loop and adapted to maintain said flux after said portion of said main winding is disconnected from said source and until the alternating current reaches a given phase of its cycle.

. 10. An electromagnetic switch adapted to control an alternating current translating circuit, comprising an electromagnet, a main winding having a portion adapted when energized to in duce a flux in said electromagnet, a shading coil mounted on said magnet, means to short-circuit said shading coil upon itself and to connect said portion of said main winding to a source of alternating current and to alternatively open said short-circuit and thereafter disconnect said portion of said main winding from said source, and an adjustable oscillating circuit connected in series relation with the entire main winding in the form of a closed loop and adapted to maintain said flux after said portion of said main winding is disconnected from said source and until the alternating current reaches a given phase of its cycle, said oscillating circuit including a resistance, a reactance and a capacitance electrically connected in series relationship to each other.

11. An electromagnetic switch adapted to control an alternating current translating circuit, comprising an electromagnet, a main winding having a portion adapted when energized to induce a flux in said electromagnet, a shading coil mounted on said electromagnet, means to shortcircuit said shading coil upon itself and to connect said portion of said main winding to a source of alternating current and to alternatively open said short-circuit and thereafter disconnect said portion of said main winding from said source, an adjustable oscillating circuit connected in series relation with the entire main winding in the form of a closed loop and adapted to maintain said flux after said portion of said main winding is disconnected from said source and until the alternating current reaches a given phase of its cycle, said oscillating circuit including a resistance, a reactance and a capacitance electrically connected in series relationship to each other, and said reactance and said capacitance having means individual thereto to vary the effective values thereof at will.

12. An electromagnetic switch adapted to control an alternating current circuit for welding or the like, comprising a set of normally open contacts, a closing electromagnet and a lock-out electromagnet associated with said contacts, each of said electromagnets having a main winding adapted to induce a flux therein and a shading coil, means individual to each of said magnets adapted to short-circuit the respective shading coil upon itself and to connect the main winding to a source of alternating current and to alternatively open said short-circuit and to thereafter disconnect said main winding from said source, an adjustable oscillating ries with the main winding of said closing magnet in the form of aclosed loop and adapted to maintain the flux therein after said main winding is disconnected from said source and until the alternating current in the translating circuit reaches a given phase of its cycle, said oscillating circuit including a resistance, a reactance and a capacitance electrically connected in series-relationship to each other, and means subject to manual control to simultaneously initiate energization of one and deenergization of the other of said electromagnets, and vice versa.

13. An electromagnetic switch adapted to control an alternating current circuit for welding or the like, comprising a set of normally open contacts, a closing electromagnet and a lock-out electromagnet associated with said contacts, each of said electromagnets having a main winding adapted to induce a flux therein and a shading coil, means individual to each of said magnets adapted to short-circuit the respective shading coil upon itself and to connect th main winding to a source of alternating current and to natively open said short-circuit and to thereafter disconnect said main winding from said source, an adjutable oscillating circuit connected in series with the main winding of said closing magnet in the form of a closed loop and adapted to maintain the flux therein after said main winding is disconnected from said source and until the alternating current in the translating circuit reaches a given phase of its cycle, said oscillating circuit including a resistance, a reactance and a capacitance electrically connected in series relationship to each othe and reactance and said capacitance having means individual thereto to circuit connected in se-.

alter-- -tacts, a closing vary the effective values thereof at will, and means subject to manual control to simultaneously initiate energization of one and deenergization of the other of said electromagnets, and vice versa.

=14. An electromagnetic switch adapted to control an alternating current circuit for welding or the like, comprising a set of normally open conelectromagnet and a lock-out electromagnet associatedwith said contacts, said closing electromagnet having a main winding :1 portion of which is adapted when energized to induce a flux in said electromagnet, said lock-out' electromagnet having a main winding adapted when energized to induce a flux therein, each of said electromagnets having a shading coil, means associated with said electromagnets jointly, said means being operable to short circuit upon itself the shading coil of said closing electromagnet and to simultaneously connect said portion of the main winding thereof to a source of alternating current, said means being operable alternatively to short-circuit upon itself the shading coil of said lock-out electromagnet and to simultaneously connect the main winding thereof to said source of alternating current, an oscillating circuit in the form of a closed loop adapted to maintain the flux in said closing electromagnet after said portion of the main winding thereof is disconnected from said source and until the alternating current in the first mentioned circuit reaches a given phase of its cycle, said oscillating circuit including a resistance, a. variable reactance and a variable condenser electrically connected in series relationship to each other and to the entire main winding of said closing electromagnet, and said means associated with said electromagnets jointly being subject to control by a single manually operable switch to simultaneously initiate energization of one and deenergization of the other of said electromagnets, and vice versa.

JURG A. SENN. CARROLL STANSBURY. 

